ISL6131 Datasheet, PDF (7/13 Pages) Intersil Corporation – Multiple Voltage Supervisory ICs

ISL6131, ISL6132
Applications Usage
Using the ISL613XSUPEREVAL2 Platform
The ISL613XSUPEREVAL2 platform is the primary
evaluation board for this family of supervisors and is
designed to support the ISL6131, ISL6132. In addition, it
also supports the ISL6125 sequencer as it has open drain
RESET# outputs similar to the STATUS outputs of the
ISL6131 and ISL6132.
The ISL613XSUPEREVAL2 is shipped with a ISL6125
soldered into the SMD channel 2 position and with 2 each of
the ISL6131 (1 socketed) and ISL6132 loose packed. The
four resistor divider strings are set so that VMON = VMON
Vth (0.633V) once supplies are 2.10V on the IN_D, 1.27V on
IN_C, 4.27V on IN_B and 2.78V on IN_A. On the ISL6131
these are the 4 UV levels at ~85% of 2.5V, 1.5V, 5V and
3.3V respectively.
LEDs turned off are the PGOOD high indicators with D4
being the ISL6131 indicator.
With V_DD ranging from 1.5V to 5V or shorted to IN_A
through JP1 and with an ISL6131 in the socket, PGOOD will
release to be pulled high once those minimum conditions are
met. See Figures 10 to 17 for performance and function
examples.
With the ISL6132 in the socket and IN_C and IN_D tied to a
common supply and IN_A and IN_B tied to a second supply
the ISL6132 will look for a voltage between 1.27V to 2.10V
on the CD pair and between 2.78V and 4.27V for the AB
pair. Once either supply meets its requirement the related
PGOOD will release to pull high and turn off the related LED.
See Figures 18 to 24 for performance and function
examples. Figures 25 and 26 illustrate the
ISL613XSUPEREVAL2 platform in image and schematic.
Using the ISL6131, ISL6132 for Negative Voltage
Monitoring Applications
The ISL6131, ISL6132 can be used for -V monitoring as it
monitors any voltage more positive relative to its GND pin.
With correct bias differential these parts can monitor any
voltage regardless of polarity or amplitude.
Using the ISL6131 for ‘Loss Less’ Sequencing
Applications
The ISL6131 can be used in a ‘loss less’ sequencing
application where a monitored output voltage determines the
start of the next sequenced turn-on. As shown in Figure 7,
VMON_A input looks at the common VIn of several DC-DC
converters and enables DC-DC_A with STATUS _A, once
both VIn and ENABLE are satisfied. VMON_B monitors the
output of DC-DC_A and when the acceptable output voltage
is reached, DC-DC_B is enabled with STATUS_B output.
This sequencing pattern is continued until all DC-DC outputs
are on, at which time PGOOD signal will be released to
indicate. 160ms delay from VMON > V_VMONVth to STATUS
high ensures stability at each step prior to subsequent turn-
on. Additional ISL6131s can be employed in parallel to
sequence any number of DC-DC convertors is in this
fashion.
VIN
VOUT
EN DC-DC_A
VIN
VOUT
EN DC-DC_B
VIN
VOUT
EN DC-DC_C
ABC
STATUS
PGOOD
VMON_A
VMON_D
VDD
ENABLE
ISL6131 VMON_C
VMON_B
GND
FIGURE 7. ISL6131 ‘LOSSLESS’ SEQUENCING
CONFIGURATION
Using the ISL6131 for System Voltage and Over
Temperature Monitoring
Being a multivoltage monitoring IC the ISL6131 can also be
used to monitor over temperature as well as voltage for a
more complete coverage of system health. Using a Negative
Temperature Coefficient (NTC) passive device in place of
one of the resistors in a VMON divider provides over
temperature monitoring either locally or remotely.
Evaluations of this application configuration have involved
the QT0805T-202J, QT0805Y-502J and QT0805Y-103J
NTCs from Quality Thermistor.
ISL6131 over temperature monitoring is not as accurate as
specific temperature monitor ICs but this implementation
provides a cost efficient solution with 5% tolerances
achievable.
See Figures 8 - 9 for over temp sensing configuration and
operation results. In this example, the desired maximum
temp is 100°C. The QT0805Y-103J NTC was placed at the
end of 3 feet of twisted pair wire to emulate a remote sensing
application. From the Quality Thermistor data sheet, this
NTC device has a +25°C value of 10K and at +100°C a
value of 0.923K. An accompanying standard value resistor
of 3.83K was chosen for divider so that at 100°C, VMON
~0.633V with the bias voltage at 3.3V.
7
FN9119.4
August 17, 2010